Answer: 
Explanation:
Given
Mass of particle is 
Charge of particle is 
Electrostatic force must balance the weight of the particle
Direction of the electric field is in upward direction such that it opposes the gravity force.
Answer:
More force
Explanation:
Pressure and force are related by the equation:
where
p is the pressure
F is the force
A is the area
We can re-arrange the equation as
In this problem, the pressure is kept the same (p' = p) while the area is increased. As we can see from the previous equation, the force applied is directly proportional to the area: therefore, a greater area means also a greater force.
Application of surface tension:
1) A needle placed on water can be made to float due to the surface tension of water.
2) Mosquito eggs can float on water because of its surface tension.
3) Toothpaste contains soap, which reduce the surface tension and helps it spread freely in the mouth.
Answer:
Newton's Cradle experiment perfectly demonstrates the law of conservation of momentum which states that in a closed system, momentum before the collision is equal to momentum after the collision of the system.
As the first ball swings in the air, it gains momentum. When it strikes the second ball, it loses momentum and second ball gains equal amount of momentum. The second ball transfers the momentum to third, then fourth and till the last. The last ball when gains the same momentum swings up in the air. This continues. This experiment is done in drag free condition. This means there is no loss of momentum or opposing forces present.
The earth is considered an Open system which is B.
